C. V. Toddy, U.S. Pat. No. 2,937,406 describes generally the fluid pressure core technology used by the industry in curing new tires and retreading old tires. In this technique, fluid pressure cores, such as full circle or sectional air bags, bladders, and the like, are inserted within uncured or green tires and like articles during vulcanization to force the external surface of the article into engagement with the mold and to exert pressure thereon. The Toddy patent discloses that it is critical to lubricate the interface between the external surface of the bag and the internal surface of the tire, especially beneath the shoulder areas of the bag because of the high frictional forces developed. Unless relieved, these forces lead to substantial reduction of tire gauge at this key area and eventually cause premature failure of the bag. Toddy proposed to overcome the friction by molding integral lubricated rubber layers into the air bag, but this is difficult and expensive to accomplish. Another approach to a green tire lubricating and bag release agent is that disclosed in Cekada, U.S. Pat. No. 3,532,624 in which a composition comprising a silicone fluid, a polyol, particulate mica, and 25 to 55% by weight of a hydrocarbon solvent is sprayed on the surface of a conventional bag, i.e., one which does not include lubricated strips, just before expansion into the green tire. All hydrocarbon solvents are flammable, many are toxic and most cause deterioration in the quality of the air, soil and water and thus are difficult to dispose of. Illustrative of the volatile, flammable, toxic state-of-the-art solvents described in Cekada are those boiling below 200.degree. C., such as cyclohexane, toluene, gasoline, petroleum naphtha, and the like.
Thus, the tire industry has a demonstrated need for an easy to apply, efficient and non-polluting inside green tire lubricant and release agent. An ideal release agent should prolong bladder life, release effectively, both initially and after long term aging and cut down on defects, due to air bleed problems, and the like.
There has now been discovered a family of compositions, based on silicone emulsions, which provide the above-enumerated advantages. These compositions possess all of the important properties necessary for a preformulated green tire release agent and, because they are water based, there are no fire or health hazards or environmental problems in connection with their use.